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KRAKATOA Hydro- Volcanic Explosion and Tsunami

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1 KRAKATOA Hydro- Volcanic Explosion and Tsunami

2 Krakatoa Krakatoa exploded August 27, 1883 obliterated 5 square miles leaving a crater 3.5 miles across and meters deep. 33 ft high tsunami waves hit Anjer and Merak demolishing the towns and killing most of the people > 10,000. In Merak wave rose to 135 ft ASL and moved 100 ton Coral blocks up on the shore.

3 Krakatoa Tsunami Tsunami swept over 300 coastal towns and villages. Over 40,000 were killed by the tsunami waves. Sea withdrew at Bombay, India and killed one person in Sri Lanka. Tsunami produced by explosion and associated shock wave and pyroclastic flows.

4 Krakatoa Before and After Explosion

5 New Volcano – Anak Krakatau - 1983

6 Travel Time of Major Tsunami from 4th Explosion and Collapse

7 Area Flooded

8 Max Run-up Heights (meters)

9 Jakarta Tide Gauge Barograph Record shows early arrival of the atmos pressure waves

10 Tide Gauge Records from Atmospheric Pressure Waves

Generated by Interaction of Magma with ground water. Called Surtseyan after 1963 eruption off Iceland. Water flashes to steam and expands explosively H2O(LIQUID) > H2O(GAS) at constant volume has a 30 Kbar PRESSURE

12 Modeling Hydrovolcanic Explosions
Water described as an Explosive and a propagating detonation is modeled for hot liquid water going to gas. BKW steady state conditions of C-J state of 89 kbar, 5900 m/sec, 0.75 cc/gm, 1100o K for liquid water with kcal/mole Heat of Formation to model energy (19 kcal/mole) for hot lava heating water to ~1100o K.

13 Krakatoa Model Spherical Geometry
2 Km -3 200 m 100 m Water 500 m Hot Spot Km AXIS BASALT

14 Hydrovolcanic Explosion
0.1 sec 0.3 sec 0.2 sec

0.4 Sec 0.5 Sec 0.4 Sec 0.5 Sec 0.7 Sec 0.6 Sec 0.7 Sec 0.6 Sec

16 Krakatoa Hydrovolcanic Eruption Density Contours
1.5 Sec 1.0 Sec 2.0 Sec 3.2 Sec 10.0 sec

17 Krakatoa Hydrovolcanic Eruption X-velocity contours
0.4 Sec 1 Sec Note Strong Air shock 2 Sec 10 Sec

18 Krakatoa Hydrovolcanic Eruption Density Contours

19 4 km km WAVE Profile 8 km

20 TSUNAMI WAVE Radius Wave Height Period 4 km 130 meters 25 sec
Inside the hydrovolcanic explosion at 1.5 km radius it expands up for more than 2 km with initial pressure >25 kb

21 Did it look like 1946 Bikini Shot?
21 Kt at 27 m depth – Krakatoa megatons

22 Krakatoa The tsunamis had periods of less than 5 minutes and wavelength of less than 7 km thus rapidly decayed. The far field effects were negligible but recorded on tide gauges around the world. Caused by air shock propagating and coupling to the ocean.

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